(1) Field of the Invention
The present invention relates to focused ion beam etching apparatus using a focused ion beam to form or modify patterns, directly and without using masks, on wafer surfaces in a semiconductor device manufacturing process.
(2) Description of the Related Art
A known focused ion beam etching apparatus has a construction as shown in FIG. 1.
This apparatus includes a sample chamber 101 in which a wafer 102 is placed for processing, the sample chamber 101 being decompressed by an exhaust unit 105. The apparatus etches the wafer 102 by directing thereto a focused Ga.sup.+ ion beam 103 with an accelerating voltage of 30 keV along with chlorine (Cl.sub.2) gas acting as an etching gas. The chlorine gas is sprayed to the wafer 102 through a fine nozzle 104.
With such an etching apparatus using a focused ion beam, wafer surfaces are vulnerable to damage by the accelerated ions. There is a further disadvantage that the sample chamber 101 and wafer 102 tend to be contaminated by the etching gas such as chlorine gas directly introduced into the sample chamber 101.